Michael von dolivo-dobrowolsky



(No Model.)

M. vVON DOLIVO-DOBROWOLSKY. ALTBRNATING CURRENT MOTOR.

No. 427,978. Patented May 13, 1890.

A the other UNITED STATES PATENT OFFICE.

MICHAEL VON DOLIVO-DOBROWOLSK Y, OF BERLIN, GERMANY, ASSIGNOR TO THE COMPANY ALLGEMEINE ELEKTRICITATS-GESELLSCHAFT, OF SAME PLACE.

ALT-ERNATING-CURRENT MOTOR.

SPECIFICATION `forming' pax't of Letters Patent No. 427,978, dated May 13, 1899.

Application 4lot'l November 13, 1889. Serial No.

France June 24, 1889, lo. 199,154; in Belgium July 1,

330,159. (No model.) Patented in Germany Inch 8, 1889, Ho. 51,083; in 1889,10. 86,818; in Luxemburg July 2, 1889,1Io. 1,153; in Italy July 4., 1889, L, 456, and in Switzerland October 26, 1889,l0. 1,532.

86,818; Luxemburg July i', 188i), No. 1,153;

October :26, 1899, No. 1,532, and Germany March S, ISS), No. 51,0S3,) whereof the following is a specification.

My invention relates to the method of pro- 15 'ducing rotative motion by means of alternatingelectric currents proposed by Professor Ferraris in Turin. According to this method two or more inagne'tizing-coils or groups'of coils placed at an angle to each other are so zo connected that on one hand they are traversed by alternating currents of different phases, (such as are produced by an alternating-cnn rent dynamo in which the armature-coils are shifted in respect to each other,) and that, on hand, the result-ing magnetic eld of the. said coils travels ina determined direction of rotation. If in this rotating magnetic field is placed a conductive body capable ot` rotating-for instance, a cylinder of 3o copper or iron-it will be caused to rotat'e by the reciprocal action of the magnetic field and the Foucault currents induced in the conducting-body. An alternating-current motor of this system having a copper cylinder will,

however,

effect, although there is a well-conductive path for the Foucault currents, because the intensity ofthe magnetic field is but small.

If an iron cylinder is employed, a stron g mag- 4o netic field is obtained; but then the inconvenience arises that the electric currents are conducted much less than by copper, and that therefore too great a resistance is presented to the said currents. In order to ohviate these disadvantages, the body in which the Foucaultcurrents are induced, and which constitutes the armature of the motor, is constructed not produce a high degree tft'usefnl4 of iron and copper combined, the iron forming a body of rotation, such as a solid orhollow cylinder or a ring, while the copper is 5o employed in the shape of bars or veins traversingr or embedded into the surface of the iron and connected together at both ends by conductors of copper. 'lhe said bars are arranged in such position as to be transverse 5 5 to the direction of motion of the rotating part of the motor, (which may be the armature or the magnetizing-coils,) and also transverse to the lines of force of the magnetic field. The iron, instead of forming one solid body, may 6o in certain cases be composed with advantage of a plurality of plates or pieces of other form, and these may be insulated from each other or not. Likewise the copper bars may be re- The copper does not require to he insulated from the iron, because the object of the improvement is only to present to the Foucault currents, in addition to the iron, a path which is more cond uetive than thelatter, and thereby 7o to increase the magnetic inertia of the arma` turc.

In thc annexed drawings are shown in end views and in longitudinal sections different arrangements of armatn res carried out aceording to my invention.

According to Figures 1 and 2 the armature consists in an iron cyliudera, fixed ou a shaft (l and provided with three rows of perforations parallel to its axis. Into the said per- 8o forations the copper .bars c are inserted, and Vthese bars are cenductively connected together at both ends by thccopper disks Z). 1f an armature of this description is placed in thev rotating magnetic field, such as may be produced by the poles P 1, it will be perceived that the bars c are transverse to their direction of motion and also transverse to the line l 2, representing the direction of the lines' of torce of the said field iu a given moment.

. The armature shown by Figs. '3 and 4 differs from the foregoing only in this, that there isbut one row of bars c. connected together by flat rings b.

placed by bundles of strips or wires of copper. 65l

Figs. 5 and (i represent an armaturel in which the copper bars c are embedded in grooves cnt into the periphery of the cylinder a., the conductors whcrehy'the bars are connected together at their ends having in this arrangement also the form of fiat rings.

Figs. '7 and 8 are sectional views of a ring armature a', arranged to rotate between poles I amll", which are opmsite to the sides or end surfaces of the ring. 'The bars rf are in this case placed radially on account of the magnetic lines of force 3 -L being parallel to the shaft (7, and-they are connected together by the copper rings b b2 being, respectively, 4outside and inside of the armature-ring. K c

With an armature of vthe described cnnstruction, the strength of the magnetic field is increased by the mass of iron of the armature, While in the veins of copper power-Eni Foucault currentscan circulate-Which in@A In an alternating-cnrren't motor, the com-- bnation, with a heid-magnet, of an ari'nat-nrc composed of an iron body of rotation,'bals,

strips, or wires of copper arranged transversely to the direction of rotation of the motor, and also transversely 1.o the lines qt force of the magnetic tiehL-and copper conductors, whereby the said bars, strips, or

vwires are connected together al'. both ends,.

substantially as described.

In. testimony whereof 1 have hereunto set my hand in the presence of two subscribing wit nesscs.

MICHAEL VON lltlhlVOJXHHHIWOLSKY.

Witnesses:

F, roN. Viamax, GEO. H. MURPHY. 

